Overload release mechanism for clutches



Oct. 26, 1954 E. THOMSON OVERLOAD RELEASE MECHANISM FOR CLUTCHES 3 Sheets-Sheet l Filed Sept. 14, 1949 .YJ I l A l W, 2

- INVENTORI MMM HIS ATTORNEYS.

Oct. 26, 1954 E THOMSON 2,692,666

OVERLOAD RELEASE MECHANISM FOR CLUTCHES Filed Sept.. 14, 1949 3 Sheets-Sheet 2 FIG, 5.

lNVENTOR:

@uw AMPM HIS ATTORNEYS,

Oct. Z6, 1954 E. THOMSON OVERLOAD RELEASE MECHANISM FOR CLUTCHES 3 Sheets-Sheet 3 Filed Sept. 14, 1949 INVENTOR:

M His ATTORNEYS.

Patented Oct. 26, 1954 /UITED FATNT OFFICE Edward Thomson, Ashley, Ill.

Application September 14, 1949, Serial No. 115,587

Claims. Il

This invention relates to clutches and is more particularly directed to clutches for machines subject to sudden or shock overloads and which contain mechanism for disengaging the clutch when that particular type of overload is encountered.

Prior to this invention, overload releases for clutches would permit the clutch to do a certain amount of slipping and allow continued operation of the prime mover and the machine operated thereby. There was no means provided for complete release of the clutch when sudden or shock overload was encountered. When this occurred the prime mover would stall, resulting in damage to the driven machine and possible damage to the prime mover. This invention provides mechanism for instantaneous release of the clutch when sudden or shock overloads are encountered, thereby preventing stalling of the prime mover and damage to the driven machine.

One of the objects of the invention is to provide release mechanism for a clutch that will disengage it after a sudden or shock overload is encountered.

Another object of the invention is to provide an overload release mechanism for disengaging the clutch upon encountering a sudden or shock overload and which will hold the clutch disengaged.

A further object of the invention is to provide a release mechanism for disengaging the clutch when sudden or shock overloads are encountered and which will enable the operator to disconnect the load from the prime mover and thereafter make whatever load adjustments are necessary for restoring normal operation of the prime mover and the machine driven thereby.

This invention consists in the provision of an inertia device for a clutch which, during normal operation thereof, will rotate therewith and, under normal overloads, will not disengage the clutch but will rotate relative to the clutch when it encounters sudden or shock overloads and will also operate the lever or linkage mechanism that disengages the clutch, thus avoiding stalling or choking of the prime mover.

In the drawings:

Fig. 1 is a vertical sectional view of a disc clutch embodying the invention,

Fig. 2 is a sectional view taken along the line 2-2 of Fig. 1,

Fig. 3 is an enlarged detail View of a portion of the inertia mechanism,

Fig. 4 is an end view of a modified form of the invention,

Fig. 5 is a sectional view taken substantially along the line 5 5 of Fig. 4,

Fig. 6 is an end View thereof with the clutch disengaged,

Fig. 7 is an end view of a modied form of the clutch taken along the line I'I of Fig. 9,

Fig. 8 is a vertical section of the clutch in engaged position; and

Fig. 9 is a vertical section taken substantially along the line 9-9 of Fig. 7.

The invention is embodied in an over center clutch employed in certain types of farm tractors, in which the numeral I designates the engine flywheel suitably mounted on the crank shaft (not shown) of the tractor engine. The ilywheel is provided with a pilot bearing 2 in which one end of the driven shaft 3 is rotatably sup-- ported. A fixed pressure plate 4 is secured to the driven shaft 3 at one end thereof and held in position thereon by means of a nut 5 and a key 6. The flywheel is provided with an axially extended rim l, on the interior of which a plurality of splines 8 are formed. These splines engage the splined periphery of the driving clutch plate 9. The driving clutch plate is concentric with a sleeve Hl mounted on shaft 3 and holds the driving clutch plate in alignment with the splines 8 in the flywheel rim. The sleeve I0 is provided with splines II cooperating with a movable clutch pressure plate I2 having a bore therein whose periphery is splined for cooperating with splines II. The pressure plate I2 is moved into engagement with the driving clutch plate 9 by means of a clutch operating sleeve I3 axially moved along the sleeve Iii by a pivo-ted manually operated lever I4, one end of which engages a slip collar I5 cooperating with a collar I6 on the sleeve I3. The sleeve I3 is provided with a plurality of outwardly projecting brackets I'I to each end of which toggle lever I8 is pivotecl. The other end of the toggle lever I8 is pivoted to one end of a lever I9 pivoted to a ring 2D threaded on sleeve IIE, suitable brackets being formed thereon in which levers I9 are pivoted. These levers are provided with abutments ZI which are engageable with the thrust receiving surface in the form of a ring 22 integral with the movable pressure plate I2. The pressure plate is brought into engagement with the driving clutch plate 9 by axially moving the clutch sleeve I3 along sleeve I0 so that the pivots for the toggle lever I8 on sleeve I3 will be positioned to the left of the pivots of the toggle lever I8 in levers I9.

The overload release mechanism for the clutch comprises an inertia disc 23 provided with an enlarged rim concentrically disposed about sleeves I 0 and I3. The levers I9 extend through suitable arcuate apertures cut in disc 23 so that the disc can rotate relative to the sleeve i0. The disc 23 has a plurality of axially extended teeth 24 formed on its hub that cooperates with similarly shaped teeth 25 on the adjacent end of sleeve I3. A thrust bearing 26 is disposed between the inertia disc 23 and the enlarged portion of sleeve l0. A pair of springs2'l areconnected between bracketsZS-on-the inertia disc 23 and pins provided in suitable projecting brackets on ring 26 so that relative reverse motion of the inertia disc will be possible for restoring it toits original position. The primary function of the springs 2'! is to restore the parts to their original position after the sleeve I3 and its associated mechanism has been released.

The operation of this device is dependent upon the imposition of a shock load on the driven shaft 3 and provides for disengagement of the movableY clutch pressure plate I2 from the driving plate 9 for the purpose of preventing the stalling or chokingV of theprime mover to which iiywheel I` isconnected. Assuming that a sudden overload hasbeen imposed on the shaft f5, the disc 23 will continue its rotationwithin the limits of the arcuate slots but relative to sleeve i6. When this action takes place, teeth 2Q on the hub of disc 23 and they teeth on the end of sleeve i3 will cause this4 latter sleeve to move outwardly, thus placing the pivots in brackets i? to the right of the pivots between toggle levers i8 and lever i9. This movement is suicient for the purpose of disengaging the clutch and permitting the prime mover to continue its operation and enabling the tractor operator to remove the cause of the overload, thereby preventing damage to the prime mover or to the machine being driven thereby.

A modified form of the invention is illustrated in Figs. 4', 5 and 6 which comprises a driving pulley 30 having a belt 3l thereabout that receives power from a suitable prime mover (not shown). The pulley 30' is rotatably supported on a bearing sleeve 32 held on shaft 33 by a screw andwasher combination 34. The pulley is provided with a pair of pins 35 on the outer ends of'whichlevers 36. are pivotally supported. These levers are providedwith hooks 3? engageable with ratchet teeth 38 on disc 39, constituting the driven member of the clutch in conjunction with shaft 33;

The overload release mechanism comprises an inertia disc 46 provided with an axially extended rim and mounted'on sleeve 32 and having arcuate slots 4| therein throughr which pins 35 extend, thus permitting the inertia disc 40 to rotate relative to the pulley 30, the slots determining the extent of relative rotation. Levers 36 engage pins ll'when the clutch is engaged, as shown in Fig. 4, and pins 42 engage levers 'J6 when the clutch is disengaged, as shown in Fig. 6. Pins 42 nold the' latches in engaged position and pins 42 limit the outward movement ofthe latches.

Compression springs 43 are disposed between suitable abutments on the inertia disc 46 and pulley 30. The springs43 hold the clutch in engaged'or disengagedposition; After the inertia disc 16 hasbeen rotated relative to the pulley 36, thereby placing springs 43 on opposite sides of the shaft 33l axis, it is necessary to manually reversely rotatethe inertia disc for the purpose of reengaging the clutch. The springs 43 are disposed on opposite sides of shaft 33 and suitably secured thereto. When the pulley 36 and the inertia disc 40 rotate relative to each other, the springs are compressed a maximum amount when 4 in substantial alignment with each other through the axis of shaft 33. During the relative motion, the springs pass through the radial alignment, also called over-center movement, they expand, and in so doing, assist in completing the relative motion and then hold the parts in such position until movedfreversely. These springs act in the same manner as they doin prior art over-center clutches.

The pulley 30 is rotated in a counter-clockwise direction and when a sudden or shock overload is imposed on shaft 33, the inertia disc 40 will rotate relative to pulley 30 and sleeve 32. This action will cause the levers 36 on hooks ST to be lifted outwardly by engaging pins 42', thus enabling them to clear the ratchet teeth 38 on disc 39, thereby permitting the pulley 30 and the inertia disc 40 to rotate relative to shaft 33 which action disconnects the power source from shaft 33, thereby preventing possible damage to the prime mover or to the machine driven thereby.

Another modied form of the invention is shown in Figs. 7 through 9 in which 44 is a pulley driven by a belt 45 connected to a suitable prime mover (not shown). The pulley 44 is rotatably mounted on a shaft 46 to which a lixed clutch pressure plate Mis secured, as by welding or other suitable means, the disc being engagcable with pulley 46. A movable clutch pressure plate 43 is disposed on the opposite side of pulley 44 and is splined to a sleeve 49 axially slidably mounted on shaft 46. The sleeve 66 has a clutch spool 50 slidablv mounted thereon and engageable with a collar 5| integral with sleeve 49, the clutch spool 56 being splined to the sleeve 49. A spring- 52 is disposed between the clutch and the spool 5D. A disc 53 is clamped to shaft 46 by a screw 55. The spring 52 is disposed within the bore 56 eut in the clutch spool 5D and abuts the base of the bore and the disc 53. The spool 6e is moved axially of shaft. 46 and sleeve 49 by means of a lever 5'! provided with clutch spool pins 58 projecting into groove 59. in clutch spool 56. The movement of lever 57 about its pivot pin 66, in a clockwise direction; will move spool 56 on shaft 46 and sleeve 19 against the action of spring 52 for disengaging the pressure plates 41 and 43 from pulley 44. When the lever 5? is rotated about pin 60 the spool is moved away from the inertia disc 6I. This relieves pressure between plate 48 and the pulley 44, thus permitting relative rotation therebetween. The spring 52 will reengage the clutch upon release of the lever 51.

The shock overload release mechanism comprises an inertia disc 6l provided with an axially extended rim and rotatably supported on sleeve 4S. Thisdisc is provided with a plurality of circularly arranged apertures 62 which are engageable by projecting pins 63 integral with the clutch spool 50. The number of pins 63 is preferably equal to the number of apertures 62. Suitably aligned abutments 64 and 65 are provided on the inertia disc 6l and movable pressure plate 43, respectively, springs 66 being disposed therebetween. A pair of lugs 6'! and 6B are provided on the movable pressure plate 48 and the inertia disc 6 l, these lugs being normally held in abutting engagement with each other by the springs 65. The lugs limit relative rotation between the inertia disc and the clutch pressure plate 48 when the springs 66 restore them to their original positions. They rotate relative to each other by reason of the springs 66 afterthe pins have been withdrawn from apertures 62 by movement of theY clutch spool 5B upon actuation of lever 51.

When the clutch is engaged, pins 63 bear against the disc on the surface thereof between apertures 62. The spring 52 then acts against the inertia disc 5l and movable pressure plate 48, thereby causing it to clamp pulley 44 between the pressure plates so that shaft 46 may be driven thereby.

Assuming that the prime mover has been sub-V,

jected to a sudden overload, pulley 44 will have its motion arrested. The inertia disc 6l will continue to rotate and in so doing pins 63 will slip over the inertia disc until they are aligned with apertures 62. The spring 52 will cause the pins to enter apertures 62 and move the spool 50 until it engages collar 5|, whereupon the pressure between plates 41, 48 and the pulley 44 will be relieved and disengage the clutch, as shown in Fig. 9, thus permitting the pulley to continue its rotation without stalling or choking the prime mover. When the pins 63 enter apertures 62, spring 52 will move the clutch spool into engagement with collar 5|. The spring cannot now move the inertia disc 6l into engagement with the movable clutch plate, thereby prevent ing engagement of the clutch. The springs 56 will restore the clutch parts to their normal operative positions in which lugs 61 and 68 are in contact after release of the overload and upon manual disengagement of the clutch, lugs 6'! and 68 then reengaging, as shown in Fig. '7, thus placing the clutch in condition for formal operation.

What I claim is:

l. A shock load responsive clutch comprising a driving member, a driven member, levered means freely pivotally mounted on one of said members for movement about a xed axis into and out of a position effective for holding said members in engagement, an inertia device disposed about said driven member and capable of movement relative thereto, said inertia device having movement independent of but engaging said levered means to move the latter upon said relative movement for disengaging said driving and driven members when a shock load is encountered and spring means operably connected between said driving and driven members and adapted to retain said members disengaged following a shock load.

2. A shock load responsive clutch comprising a driving member and a driven member, levered means pivotally mounted on one of said members to be angularly movable between positions to control engagement and disengagement of said clutch members, an inertia device disposed adjacent said levered means, said inertia device being movable independently of said levered means for operating said levered means into clutch disengaged position when said clutch encounters a shock load and spring means operably `connected between said driving and driven members and adapted to retain said members disengaged following a shock load.

3. A shock load responsive clutch comprising a driving member, a member connected to said driving member and adapted to pivot about an axis moving with said driving member, a driven member, a member fixed to said driven member to move therewith in xed relation, said movable and fixed members being adapted to have engagement in the operative condition of the clutch with the driving member driving the driven member, and an inertia device operable normally with said members in the operative condition of the clutch and capable of movement relative thereto in response to shock load conditions, said inertia device being located adjacent said movable .member and being adapted to pivot said movable member about its axis to eect disengagement of said xed and movable members when a shock load is encountered.

4. A shock load responsive clutch comprising a driven member provided with a plate having teeth thereon, a driving member supported on said driven member, latches pivotally supported on said driving member normally in position to engage said plate teeth and engage said driving and driven members, an inertia disc concentric with said driving member and capable of rotation relative to said driving member, spaced elements xed on said inertia disc for pivoting said latches from the teeth on said plate upon relative rotation of said inertia disc and driving member when said clutch is subjected to shock load to Adisengage said driving and driven members, and a pair of resilient elements engaged between said driving member and inertia disc on opposite sides of the clutch axis of rotation, said pair of elements exerting a force on said inertia disc to one side of its axis to hold said latches normally engaged with said plate teeth and upon relative rotation of said inertia disc and driving member to exert a force on said inertia disc to the opposite side of its axis to hold said latches in disengaged positions.

5. A shock load responsive clutch comprising a driven shaft, a plate provided with teeth and mounted on said shaft, a driving member supported on said shaft for rotation relative thereto, pins carried by said driving member in positions to be disposed on opposite sides of said driven member, a latch lever pivotally supported on each pin and engageable with one of the teeth on said plate, an inertia disc disposed about said shaft and having arcuate slots therein through which said pins extend, said inertia disc being capable of rotation relative to said shaft; means xed on said disc in position engageable with said latch levers, when said inertia disc rotates rela tive to said shaft upon sudden stopping of rotation by reason of a sudden shock load, to pivot said latch levers in directions in which they are released from said teeth, thereby permitting said driving member to rotate relative to said driven member, and a pair of resilient elements engaged between said driving member and inertia disc on opposite sides of the clutch axis of rotation, said pair of elements exerting a force on said inertia disc to one side of its axis to hold said latches normally engaged with said plate teeth and upon relative rotation of said inertia disc and said shaft exerting a force on said inertia disc to the opposite side of its axis to hold said latches in disengaged positions.

References Cited in the file of this patent UNTTED STATES PATENTS Number Name Date 336,588 Rice Feb. 23, 1886 1,125,646 Campbell Jan. 19, 1915 1,901,597 Hank Mar. 14, 1933 2,445,590 Stephenson July 20, 1948 2,486,603 King, Jr. Nov. 1, 1949 FOREIGN PATENTS 'Number Country Date 18,316 Great Britain 1914 903,072 France 1945 

